Electromagnetic induction is a passive electrical process. There are also no active electrical components amplifiers, impedance converters, etc.
Ribbon mics typically do not have any active components, so they do not require any phantom power. Like the majority of miniature lavalier microphones, DC-biased electret microphones are certainly active but do not require phantom power. Rather, these mics work on a DC-bias voltage. Tube microphones are also active microphones but require more power than phantom power can provide.
Tube microphones require external power supply units to power their active components tubes and capsules properly. However, many electret mics require phantom power to function properly. These electret mics are generally studio-type microphones but range from consumer to professional-grade. Electret condenser microphone capsules are built with electret material in their design and are quasi-permanently charged.
The electret a portamento between electric and magnet material maintains a permanent charge across the condenser capsule. Therefore, external power like phantom power is not needed to polarize the capsule of electret microphones. True FET condenser microphones nearly all require phantom power. For the most part, true condenser microphones are studio-grade microphones, so phantom powering should be readily available in more situations where a true condenser is used.
Like the electret microphone, true condensers require phantom power to properly power their impedance converters FETs and other active electrical components. Unlike electret capsules, true condenser microphone capsules require an external polarizing voltage. This voltage is supplied by phantom power as well. Active ribbon mics are passive transducers since they still convert sound to audio via electromagnetic induction. However, the low-level mic signal from the ribbon element is processed and amplified by active components before the audio signal is outputted from the microphone.
These active components impedance converters, amplifiers, etc. Phantom power is a positive voltage applied to both signal conductors of a balanced cable. Both conductors are fed through resistors of equal value:. The matched resistors must be matched within 0. Two specialized variants of phantom power have been developed for specialized applications:.
A common example of a balanced non-XLR cable that passes phantom power is the typical TRS cable used in a studio patch bay. Not only do they connect and disconnect more easily, but their size allows for more patching pathways in a smaller patch bay unit. These TRS patch cables do not generally plug directly into a phantom power source or directly into a microphone. Rather, the patch cables are used in routing setups and will pass audio and phantom power from one point to another.
This reason is electrical shorting or the lack thereof. XLR cables are designed with 3 pins. The audio pins 2 and 3 are equal lengths, while the ground pin 1 is slightly longer. This means that when an XLR connector is connected, it is grounded before the audio and phantom power circuit is completed. Because pins 2 and 3 are equal lengths, they are connected simultaneously, and no shorting occurs. So when connecting a TRS plug into a TRS jack, the tip of the plug first hits the sleeve, then the ring, then the tip of the jack.
The ring of the plug follows, hitting the sleeve before connecting to the ring of the jack. However, when physically connecting or disconnecting these TRS jacks, we cause electrical shorts for example, when the tip connects to the ring. These shorts may very well cause improper flow of phantom power, which can harm the microphone. However, it is possible for phantom power to damage microphones.
It is important to know how phantom power may negatively affect microphones, so we are better equipped to use P For example, some multi-channel mic preamps can only apply phantom power across multiple channels rather than on a per-channel basis. Knowing whether a microphone can handle phantom power or not is essential in these situations. The situations that could potentially cause phantom power to damage a microphone include:.
Electrical shorting, which was previously mentioned, will momentarily send the phantom power voltage up one audio conductor rather than both. Even an instant of electrical shorting can cause the DC voltage to enter the wrong parts of the microphone and damage the mic.
Power surges can overload the phantom power circuit. The spike in electrical current can fry certain wires or components within the circuit. Power conditioners are always advised in the studio or any other situation where expensive microphones and audio equipment are being used. Phantom power requires a balanced connection to work properly. If phantom power is forced through an unbalanced cable to an unbalanced microphone, the 48 volts on the audio cable may very well overload the microphone and cause serious damage.
Unbalanced microphone examples include many karaoke microphones and even many of the professional DC-biased lavalier mics on the market. One such example is the output-coupled transformer which only passes AC voltage the mic signal.
Having a transformer at the output of the microphone will protect it from proper phantom power. Some dynamic microphones are transformerless but can handle having phantom power enter their passive circuitry. So most professional-grade microphones that have balanced outputs will not be damaged by proper phantom power. One common concern with ribbon microphones is the potential for phantom power to destroy the fragile ribbon diaphragm. Passive ribbon microphones, therefore, are designed with output transformers to protect them from DC voltage.
The microphones that would likely get damaged by phantom power, even if applied correctly, are unbalanced. Think belt-pack lavalier microphones and karaoke mics. Fortunately, these microphones do not have XLR connectors, so it would require some effort and adapters to even apply phantom power to the microphones in the first place. Like professional microphones, the majority of wireless microphone receivers have balanced outputs.
These output circuits will typically have the necessary phantom power blockers to keep the receivers safe. There are some microphones on the market that offer the option of powering the mic with batteries or phantom power. It is advised, with these microphones, that we remove the internal batteries when phantom powering is used to avoid the potential corrosion and leakage of the batteries. Phantom power came about in the s when mic manufacturers began using transistors instead of vacuum tubes in their condenser microphones.
Phantom power came about to power these solid-state mics via the same cable that carries the mic audio rather than with an external power supply like tube microphones. In , Lee De Forest invented the first triode vacuum tube the basic tube used in microphones. The triode vacuum tube patent was awarded in Tube microphones, by their design, require a lot of power to polarize their capsules properly and heat their vacuum tubes.
This power is supplied by external power supply units that plug into the wall. As the diaphragm vibrates, the charge on the plate varies. This electrical signal is transmitted down a cable to the mixer etc. To charge this plate, the microphone needs power unlike the dynamic microphone. Plug in your condenser microphone, and switch on phantom power on the correct channel, and bingo- your microphone will spring to life. Also, back electret type condensers can sometimes use batteries for power instead of phantom power.
Many of this type of microphone will also accept phantom power too, however. Simply plug-in your condenser microphone and switch on phantom power on the correct channel.
Registered in England. Company registration number VAT no. By using the Dawsons website you agree to our use of cookies to improve your experience and our services Close. However, some older mixers and cheaper audio interfaces may not have phantom power. In this case, an external phantom power supply can be added between the condenser mic and the preamp. A dynamic microphone, like the SM58 , does not require phantom power because it does not have active electronics inside.
Nonetheless, applying phantom power will not damage other microphones in the vast majority of cases. The reason is that modern dynamic microphones are designed to accept phantom power without issues, but we advise checking your manual or consulting with the manufacturer first before connecting; particularly if you have a ribbon microphone. Condenser microphones made in the s, s, and s required a special power supply to operate. This power supply would often be located quite near the microphone and was usually large, heavy, and cumbersome.
In the s, work began on a new powering concept that would eliminate the need for a separate power supply.
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